OPC-UA Client - Instance & item setup
How to setup an OPC-UA Client in SIA
Parameters
When using the OPC-UA Client Connector both the instance and item have specific parameters. These parameters are required as they are needed to establish connection and to identify which objects to read from.
Instance
The instance needs the following parameters to establish a connection to the OPC-UA Server:
| Parameter | Description |
|---|---|
| Address | The address of the server, including endpoint opc.tcp://75.152.105.54:48010/myEndpoint |
| User name | The user name to use when connecting to the server, leave blank for connecting without username/password |
| Password | The Password to use with the username |
| Security Mode | The security mode used for connecting with the server. Supported security modes:
|
| Security Policy | Security policy mode used by the OPC-UA server for encryption. Supported policies:
|
| Timestamp | Whether to use the servers timestamp or SIA Connect's local timestamp given by the time of when the value was read |
| Certificate | Authentication certificate issued by OPC-UA server. Certificates can be uploaded by follow these steps: Manage files for Connectors |
| Key | Authentication key issued by OPC-UA server. Keys can be uploaded by follow these steps: Manage files for Connectors |
Keys and certificates
Accepting certificate on OPC-UA server
If the OPC-UA server is configured with an encrypted connection (security policies & mode is set) the OPC-UA server needs to accept the connection certificates from SIA Connect in order to establish connection.
On first boot the Connector will generate a certificate and key to be used with connecting, these certificates is used for secure connections to the OPC-UA server and needs to be accepted on the server side. The certificates can be downloaded from the Connectors page under files by following this guide Manage files for Connectors.
Item
The item parameters that are needed to connect to the objects in the OPC-UA server
| Parameter | Description |
|---|---|
| Identifier | The identifier to adress the item. The connector will figure out whether it is a numeric, guid or string (in that order) eg with namespace included:
Reading arrays When reading arrays, the index of the array must be specified in the identifier:
|
| Floating Point Precision |
Represents the amount of digits following the decimal-point in floating point values |
| Access Level |
Current read/write Read and write the current value of the tag History read Read the tag's historical data. All values stored within the given time will be read, presented as an array of JSON objects |
| History From |
History read from time in Epoch time Can be used either with a static Epoch timestamp, or with a negative value representing the amount of milliseconds from the current time |
| History To | History read to time in Epoch time Can be used either with a static Epoch timestamp, or with a 0 representing the current time |
| History No Value Handling |
Keep latest non-empty value If there is no historical value in the time-constraints, SIA will retain the latest value - even if the latest value is older than the time given Use empty value If there is no historical data in the time-constraints, the item will have an empty value |